Water has a number of important industrial uses, including its use as a medium to remove heat from process equipment and its use in the generation of steam. Unfortunately, untreated water cannot be used directly for these or other purposes in most instances due to the presence of various impurities which may prevent effective heat transfer, interfere with fluid flow, or corrode process equipment. In such cases, treatment of the water is required to assure efficient equipment operation. For example, compounds which inhibit scale formation are commonly added to cooling tower and boiler waters to prevent the formation or deposition of scale on equipment in contact with these waters.
Most industrial waters contain metal cations, such as calcium, barium, magnesium, and sodium and anions, such as bicarbonate, carbonate, sulfate, phosphate, silicate, and fluoride. When combinations of these anions and cations are present above certain concentration limits, reaction products precipitate on the surface of equipment in the system containing the water, forming scale or deposits. This precipitation is an expensive problem in many industrial water systems, causing delays and shutdowns for cleaning and removal.
Formation of scale compounds can be prevented by insuring that the solubility limits of cation-anion reaction products are not exceeded. Certain water-soluble polymers, including polymers derived from unsaturated carboxylates and unsaturated sulfonates, or their salts, are useful for this purpose. When these polymers are added to industrial waters to inhibit scale, their concentrations must be frequently determined to properly monitor system performance. If too little of a polymer is present, the system may not be adequately protected; if too much of a polymer is present, the treatment may not be cost effective. For a given system, there is an optimal treatment concentration which must be maintained. It is therefore desirable to be able to quickly and accurately determine the concentration of treatment chemicals in water systems.